Bacteria in your toothbrush
The hypothesis that toothbrushes kept in Listerine solution have the least amount of bacteria, is proven to be true.
Proper tooth brushing techniques will help to get rid of plaque and bacteria that are responsible for tooth decay and gum disease. Using toothpaste which contains fluoride helps to strengthen one's teeth against decay. It also helps to remove stains from the teeth and gives us clean, fresh breath.
To improve the reliability and accuracy of our results, a larger sample of participants should be used.
This science fair project may be repeated, this time, with taking a swab sample from the mouth after gargling with water, gargling with mouth wash and gargling with Listerine and comparing the bacteria content.
Modify the science project experiment, using saltwater, lime juice and sterilized water.
Mouth bacteria, it’s a jungle in there - http://www.brighthub.com/science/genetics/articles/45935.aspx
Toothpaste - http://www.dentalgentlecare.com/toothpaste.htm
Basic safety requirements